Bi-axial bias weaving machine and material thereof

ABSTRACT

The present invention involves a Bi-axial bias weaving machine and two dimension woven structures (material) having interlaced bias strands. The material includes plain, twill and satin structures made of two bias flat strands (tape) interlacing each other at particular angles (30-60). The weaving machine includes bias holders assembly, chains, bias rapiers and take-up assembly. The embodiment of this invention may be utilized to produce high performance fabrics such as textile performs for aerospace composites.

BACKGROUND OF THE INVENTION

The present invention involves a Bi-axial Bias weaving machine and two dimension woven structures (material) having interlaced bias strands. The material includes plain, twill and satin structures made of two bias flat strands (tape) interlacing each other at particular angles (30-60). The weaving machine includes bias holders assembly, chains, bias rapiers and take-up assembly. Each Bias holder is responsible for holding the flat bias strand and shedding in order to produce the desired structure such as plain, twill and satin. Chain holds the bias holders assembly and rotate in order to make production continuous. Rapier is mean to insert the bias strand into the shed produced by Bias holders assembly. Bias strand feeding set-up is connected with rapier assembly. The embodiment of this invention may be utilized to produce high performance fabrics such as textile performs for aerospace composites.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to weaving machine designs for biaxial bias fabric (BBF) manufacturing for Fibre Reinforced Composites. The BBF comprises two sets of bias strands interlaced with each other at bias angle. Both bias strands are fed at opposite directions, meet at center point of fabric and make biaxial bias fabric by interlacing with each other.

Bias strand is meant as an assembly of continuous filaments in the form of tow or tape. Bias angle of strand is meant the direction of the strand interlacement at angles 30° to 60°.

Textile composites are well known to several applications such as automotive, marine, transportation, civil infrastructure and off-shore due to high strength to weight ratio. Textile composites are made of textile preform consolidated with resin. Strand orientation in textile preform has great influence on properties of preform in terms of strength in one or more directions and suitability of shaping. In order to satisfy the strand orientation requirements at bias angles such as 45°, conventional woven fabrics are cut at oblique orientation and this cut piece fabric is referred as bias fabric. Such method has several drawbacks including intensive labour cost, huge wastage and compromised mechanical properties.

In W.I.P.O. Patent No. 2010/004284 A1, there is a disclosed machine relating to a method of weaving a multi-axial fabric and a loom for weaving a multi-axial fabric. This method comprises 4 layers in a woven fabric. The first layer is a bias structural layer at +45° direction, the second layer is a bias at −45° direction, third layer is weft yarn at 90° direction and finally binder yarns and warp yarns are at 0° direction. The binder yarn is the only yarn which binds all other yarns. Each binder yarn is guided with guide members in order to make the shed and beat-up the weft yarn. Rapiers are used to insert these weft yarns. During continuous operation of loom, rotating wheel feed assemblies carry bias packages. These packages release bias yarns engaged with moveable plates in order to make bias structure.

In one form of bias yarn traversing device disclosed in U.S. Pat. No. 5,137,058, the method aims to weave fabric which includes a warp layer, bias threads and a vertical thread arranged in a thickness wise direction of the fabric such that it perpendicularly intersects the warps. The fabric structure contains a bias thread layer that is composed of a large number of continuous bias threads which are arranged symmetrically to each other. Each pair of bias thread layer makes a set. The engaging positions of the bias threads are moved by a predetermined pitch in opposition direction to each other. Such movement of the engaging position and insertion of vertical threads are performed alternately. Bias yarns are engaged by screw shafts which rotate and move to and from to move the bias thread with the help of grooves of screw. There is a tendency of the yarn to slip form grooves. Here, as the bias yarn reaches the edge of the fabric, it is folded downward and travels back to the opposite edge. Such folding causes non-uniformity.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows the perspective drawing of Biaxial Bias Weaving Machine 100 which manufactures the biaxial bias fabric with different structures such as plain, twill and satin. This is in contrast to method of stitching or knitting designed to sew together 2D layer of bias plies. This exemplary embodiment offer s several advantages over the known art, including:

-   -   1. The elimination of knitting and stitching mechanism remove         the change of fibre damage within the woven preform, achieve         higher damage tolerance and in-plane shear loads for composite         materials.     -   2. The elimination of cutting of orthogonal woven fabric in         oblique direction in order to make then bias fabric, reduces the         huge scrape and fabricating cost by avoiding the cutting and         hand-layup process. It further reduces possible delamination         failure of the composite structure and achieves higher damage         tolerance.

FIG. 2 depicts the biaxial bias woven fabric of the invention shown schematic in which a piece of cloth 1 can be seen with length L and definite width W. Relative to the width, the length L can be considered as being indefinite. The manufacturing process is capable of continuous production with uniform structural characteristics over the length of BBF.

The cloth is woven with two sets of strands 2 and 3 which are interlaced with suitable weave design such as plain, twill or satin. The strands 2 and 3 extend along respective directions +X and −X which are oblique relative to the direction of length L. The directions +X and −X are preferably symmetrical and can vary between 30° to 60°, however ±45° direction is preferred for following detailed description for reference purpose.

According to another characteristic, the strands 2 and 3 are of finite length and are interfered with selvedges la and lb. The individual strands 2 and 3 can be made of any suitable material such as glass, kevlar and carbon fibres. The selvedges la and lb can be made of suitable coated material 4 or made of cords. The suitable coated material is applied during manufacturing of BBF at both sides 1 a and 1 b in order to hold the cut ends of strands 2 and 3 firmly.

The cloth 1 of width W can be manufactured equivalent to width of cloth made on any conventional weaving machine. According to crucial and essential characteristics in the meaning of invention, the cloth 1 is interlaced with two sets of strands 2 and 3 none of which has any joint, twist or knot. The strands 2 and 3 are straight, wider in width and flat in shape; both strands remain flat under all manufacturing circumstances and have no twist over the length 1 of cloth 1. The manufacturing process is continues and length L of cloth 1 is indefinite.

FIG. 3 shows exemplary biaxial bias weaving machine 100 which work on similar basic primary motion of conventional loom such as shedding, picking and beat-up. However it does not have same elements as in conventional loom. The present invention weaving machine 100 has unique elements: rotary chain 101 and 151, an array of bias holders 111 and 161, shedding actuators 121 and 171, gripping actuators 141 and 191, set of rapiers 131-181 and Take-up assembly 300. Almost every element has two different positions, parallel to each other and acts individually. For better understanding and clarity, following details is discussing only one side of weaving machine 100 and opposite side may be considered as repetition of acts.

FIG. 4 depicts embodiment where array of bias holder 111 or 161 are separated with two rotary chains 101 and 151. The rotary chain 151 is designed to hold an array of bias holders 161 and rotate with intermittent motion so that basic primary motions of weaving process can be performed with designated timing. Each bias holder can be operated individually to lift the bias strand 2 or 3.

FIG. 5 depicts several designs including plain, twill and satin.

FIG. 6 depicts the bias holders 161 designed to grip the bias strands 2, creating shed 200 for rapier 131 to insert the bias strand 2 at +X direction. The bias holders 161 are independently controllable, preferably using shedding actuator 171; allowing formation of simple and complex weave designs.

FIG. 7 is a more detailed illustration of bias holder 111 or 151 and its components which are used to grip bias strands 2 or 3 and then lifting and lowering operation in order to make desired design. Head of each bias holder 111 has two gripping plates i.e bottom gripping plate 112 and upper gripping plate 114 having suitable laminated material 113 on both in order to grip the textile material properly without damaging the physical properties of textile material. Upper plate of bias holder 114 is always suppressed by spring 115.

FIG. 8 depicts the perspective view of shedding actuators 121 comprising shedding plate 122 and small rods 123. At the bottom of bias holders 111, shedding plate 122 is connected with actuator 121 which is controlled separately. The shedding plate contains plural small rods 123 to lift the designated bias holders 111 in order to make desired design of cloth. The number and position of rods 123 of shedding plate may be changed according to desired design. The set-up of rapier 131 or 181 performs three actions in weaving machine 100: firstly feeding the limited length of bias strand 2 or 3 to weaving machine 100, secondly insertion of bias strand 2 or 3 into shed 200 created by an array of bias holders 111 or 161 and thirdly beat-up of bias strand 2 or 3 to the last inserted bias strand.

FIGS. 9A, 9B, 10A, 10B, and 10C illustrate an exemplary bi-axial bias weaving machine operations sequence using machine of 100 of present invention. For clarity, the sequence of operations is discussed from only side of machine.

FIG. 9A depicts that after bias strand insertion, all bias holders and shedding actuators may retain their original position.

FIG. 9B illustrates the next step in sequence. At the beginning of this sequence, the set of rapier 181 starts moving toward near the rotary chain 101 where shed 200 size opens at maximum. The shedding plate 122 connecting to shedding actuator 121 starts lifting the desired assembly of bias holders 111 with the setting of rods 123. As a result, only designated bias holders 111 according to given weave design will engages the rods 123 of shedding plate 122 and will be lifted upwards to open the shed 200 for rapier 181.

FIG. 10A illustrates the next step in the sequence.

FIG. 10B depicts while returning to its original position, the rapier 181 has bias strand 2 still in its mouth starts coming back from take-up assembly 301 and travel to hand over the tail of bias strand 2 to designated bias holder 161 (See FIG. 10B).

FIG. 10C depicts that by changing the direction and position of rapier 181, bias strand comes closer to cloth fell position 300 and handover the head of bias strand 2 in between the gripping plates 162 and 164 of bias holder 161 and then the strand is cut with scissor S.

In this way newly bias strand 2 and 3 are inserted into sheds 200 and gripped by first bias holder 111 and 161 respectively by sequence. As both rotary chains 101 and 151 are connected with each other, thus movement in driving chain may lead to exact distance traveled by both rotary chains 101 and 102. Because of this, both rotary chain 101 and 151 may move exactly same distance with same timing. During the movements of these rotary chain 101 and 151, receiving heads 302 of take-up assembly 301 will also move with same distance on take-up stand with same timing. It is important to synchronize the movement of rotary chain 101 and 151 and receiving heads 302 otherwise it may lead to slackness in BBW fabric 1 and create the problems for other operations during manufacturing.

DETAILED DESCRIPTION OF THE INVENTION

It is an object of present invention to provide the weaving machine which permits the manufacturing of two dimensional (2D) structure of bi-axial bias woven fabric. An exemplary weaving machine includes bias holders assembly, chains, bias rapiers and take-up assembly. The apparatus includes a plurality of bias holders, each of which holds bias strand under tension. The bias holder further separates the sheet of bias strands into two layers in order to insert the opposite bias strand by rapier. At least one bias holders set is configured in a vertical position above the shed and at least on bias holders set is configured in a horizontal position below the shed. The same action is conventionally carried out by heald frames in conventional weaving machine.

The apparatus further includes two continuous chains holding a bias holder at each pitch of both chains. These chains rotate at intermediate motion and make the BBF production continuous. Both chains can be operated separately or jointly.

Two rapiers are adopted to fill the gap created by two layers of bias strands. The rapiers also perform the function of beat-up in some way. First rapier enters into gap of layers of bias strand and then handover the tail of bias strand to take-up assembly. While returning, it changes its position and come closer to last inserted bias strand and then transfer the head of bias strand to bias holder. The apparatus also comprises the take-up assembly. Tail of every bias strand is gripped by take-up assembly through any means such as sticking strip, gripping holder etc.

In another aspect, invention includes biaxial bias woven fabric which consists of two sets of bias strands interlaced with each other at bias angle. The bias angle may vary between 30° to 60°, however in order to manufacture the quasi-isotropic reinforcement for composite material, bias strands are oriented at ±45° direction. The biaxial bias fabric may be manufactured with different common structures such as plain, twill and satin. It is to be understood that foregoing general description and following detailed description are exemplary, but are not restricted, of the invention. 

What is claimed is:
 1. Bi-axial bias woven fabric, comprising; a plurality of first biasing yarn extending in a first direction; and a plurality of second biasing yarn extending in second direction, the second direction being at a first predetermined angle to the first direction.
 2. The bi-axial bias woven fabric according to claim 1 wherein the first predetermined angle is 30 to 60 degrees.
 3. The bi-axial bias woven fabric according to claim 1 wherein the second predetermined angle is 30 to 60 degrees.
 4. A method of weaving a bi-axial bias woven fabric comprising the step of; feeding of bias yarns at predetermined angles (+/−); lifting of bias yarns at predetermined angles (+/−) for desired woven structure; and, placement of bias yarns at predetermined angles (+/−) for new cloth fell position.
 5. An apparatus for weaving Bi-axial Bias woven structure which includes only bias yarns, the apparatus comprising: a plurality of rotary chains, each rotary chain holds bias holders, each bias holder supports bias strand under tension, the bias strand extending from bias holder in downstream direction; a plurality of rapiers configured to engage at least one of plurality of bias holders; and, a plurality of actuators disposed to lift the bias holders in upward direction for desired woven structure.
 6. The bias holder of claim 5, for holding bias strand under tension, as a part of bi-axial bias weaving machine, comprising two plates laminated with suitable material to hold the bias strand.
 7. The bias holder according to claim 1, wherein a bias strand is gripped in between two plates by force of spring.
 8. A rotary chain according to claim 5 for holding the bias holder, as a part of bi-axial bias weaving machine.
 9. A plurality of actuators according to claim 5 to form an opening among the bias strands that extends from the bias holder to woven products. 